NYACK, N.Y. (CBSNewYork) – Authorities said seven people were injured Tuesday in an explosion on the Nyack College campus that blew out windows and sent debris sailing.

The explosion happened just before noon at a building known as the Sky Island Lodge on South Highland Avenue.

The two-story Tudor-style building was extensively damaged in the blast, WCBS 880’s Sean Adams reported. Sky Island Lodge is both a classroom and administrative building for the college.

Cars covered in debris following an explosion at Nyack College on June 4, 2013. (credit: CBS 2)

The college said two students and five employees were taken to the hospital. None of the injuries were considered life-threatening and the school sent out a tweet saying that “Everyone is doing ok.” It was earlier reported that it was one student and six employees injured in the explosion.

Everyone is doing ok, thank you for your concerns and please continue to pray. We will have updates for you throughout this time.

“We’re just so thankful that school was out because if this was a month ago, it would’ve been fully staffed,” South Nyack Mayor Bonnie Christian told WCBS 880’s Alex Silverman

Authorities said there was a gas leak at the building, but it wasn’t clear if that was the cause of the explosion. The Rockland County undersheriff said there was still a heavy odor of gas as of 1 p.m., Adams reported.

Orange & Rockland crews were on the scene checking manholes and sewers for any gas leaks. The power was cut to the area for a time as utility workers and firefighters worked to determine the cause of the explosion.

For more than a hour after the explosion, workers from O&R detected levels of gas seven times higher than normal in manhole covers near the scene, Young reported.

The danger subsided a little after 2 p.m. and the campus evacuation was lifted at 2:30, according to a statement from the college.

“What we immediately did was isolate the area, valved off this section to shut off the gas. We also shut off the electricity so there’s no secondary source of ignition for the gas that was blowing,” Mike Donovan with O&R told Young. “Basement and first floor, it seems that those were the most heavily damaged areas. If you go up there now, the window air conditioners, for instance, are still in the building at the second floor windows. The windows are blown out mostly, but every one of those air conditioners is in there.”

The gas apparently built up in the basement of the building, which was built in the 1920s, Young reported. The location of the leak had not been determined as of 6 p.m.

O&R released a statement saying that power had been restored to all buildings except Sky Island Lodge as of 4 p.m.

Crews were testing the utility’s underground facilities to rule out any damage to service lines before beginning the restoration of gas service to the area, according to the statement.

The college is near Nyack Middle School, where students were being kept inside as a precaution, Christian said.

“A really big booming sound in the ground, kind of felt like it was shaking and everybody just like freaked out,” seventh grade student Celia Bernhardt told Silverman.

FBI spokesman Jim Margolin said authorities were investigating, but said that there was nothing suspicious about the explosion.